F1 sport carbs flooding

[Nortonnut]

Hi I had a problem with my SU carbs flooding on my F1 sport which filled the engine and whole exhaust system with fuel! I have since rebuilt these carbs with all new parts and reset float height and I was wondering why the overflow drain is blocked off on these carbs and does anyone know for sure if it would be ok to open them up again and fit overflow pipes for safety and diagnostic purposes?

[fogrider]

What happened to the floats, needles and seats to make this happen - one of the famous ethanol effects ?


Regards all, Terry

[Nortonnut]

Wear and contamination caused the problem, but I would like to know if I can unblock the overflow drains for safety sake, and if so why are they blocked off in the first place? anybody know?

[fogrider]

It's a few years since I visited the carbs in my Sport, I think they're sealed as part of a sealed induction system. I expected someone would have commented by now, I'll dig my notes out and see if I can come up with a more definitive answer.

[fogrider]

Just had a leaf through my notes, it's 5 years since I put new O rings in the SU's so can only go by memory - the layout is : the air from the conical air filters is pulled through the engine cases , into the plenum chamber, through the carbs then into the inlet ports. I think I'm correct in saying the carbs need to be sealed to ensure correct air flow through the system, can't remember if, or how, the float chambers are vented though.
Just had a look at the parts book for the Commander and R.N.'s illustrations for the F1 Sport carbs, I don't see breather tubes listed on either.
Best I can do I'm sorry to say.
By the way-
have a look inside the air filter entry tubes whilst you're at it, mine were full of rust, just waiting to be pulled into the rotor.

Maybe RN or GW might offer some more tech info ?

What's happened to Wayne ?

Regards all, Terry.

[Nortonnut]

Hi, thanks for your reply, I have just spoken to someone at Burlen and they advised me that they shouldn't be blocked off, but I believe it must be something to do with the peculiarities of the norton rotary engine and I would love to know why!

Someone must know ?

[Nortonnut]

I have now spoken to Burlen fuel systems, and Andover Norton as well as posting on the Norton rotary fb page, so far no one knows why the carbs have been modified in this way, and for what purpose, surely someone on here must know?

[racecomp]

Overflow from the carbs is a fire in the making. This one of the many reasons I like fuel injection. Crappy fuel soon turns gelatinous around the needle and seat eventually goes hard.

It’s easy for the needle to weep on first start up. It doesn’t take long to flood the outside of the engine and exhaust with fuel.

Trust me I’ve been in this situation with the racebike that was previously set up direct feed to the cabs from the fuel pump blowing the needles and seat open on Amal carbs, I’m not a fan of them unless gravity feed only.

I’m assuming the option to blank off was to allow overflow to go into the motor rather than on the outside.

I’ll do dome digging, on the F1 it’s a different setup.

[Nortonnut]

Ok thanks for the info, I am interested in fuel injection also

[racecomp]

I’ll have an efi kit that I’ll sell to the market, just remove and replace so you can aways go back to OEM. I can’t think why you would though but if for some reason a buyer wants it original.

It is quite an extensive kit with new loom, ecu, fuel supply pump and regulator, throttle bodies and injectors. The option to go ejector exhaust or keep closed loop is available. Mapping in real time with a base map pre fitted and a data logger for for online mapping.

[Nortonnut]

Thanks for your reply I am interested in this fuel injection kit, has it been thoroughly road tested, and how do the O2 sensors hold up with the oil in the exhaust system?
I would probably choose to run closed loop non ejector system

[racecomp]

No issues with 02 sensors or thermo sensors. Will show more when the kit is released for F1 Sport, I’m building a new sport motor over the next month and will fit an EFI kit to set up. I’ve not done a Sport injection as it’s different to the F1 motors, it has Commander housings with a butterfly in the intakes, F1 don’t.

[Nortonnut]

Thanks for the info and let me know when the injection kit is available please